In order to design and fabricate a welded structure, a machine component, etc. with a good balance of strength and weight in the structure, it is generally useful to know the stress distribution of these objects when a force is applied thereto.
Conventional stress distribution measuring instruments employing a photo-elastic method and employing a stress coating method are heretofore known. However, all of these instruments have disadvantages in that a thin uniform membrane of several hundred microns should be attached to the surface of the object to be measured, and therefore have difficulties in measuring the stress distribution of a large-sized structure. This is true particularly in the stress coating method, since measurement in such a method utilizes the brittleness of an organic substance and controlling the dry condition of the membrane attached to the object to be measured is very difficult. Further, the membrane itself has an unfavorable toxicity.
Thus, conventional stress distribution measuring causes a variety of inconveniences in actual use and is particularly unsuitable for the measurement of the stress distribution of large objects and actual mechanical apparatus, etc.
Accordingly, an object of this invention is to provide a stress distribution measuring instrument in which all of the above-described difficulties accompanying conventional methods have been eliminated, and in which the stress distribution of an object to be measured can be accurately measured without conducting any processing such as attaching any membrane, etc. to the object. Hence, accurate measurement can be performed irrespective of the configuration and the size of the object to be measured.